The invention relates to a method for manufacturing a flat textile structure in which a melt of a polymer material is changed to the form of fibers with the aid of a spinning rotor and in which the fibers are then combined and solidified to form a flat structure.
Fleece-spinning methods permit manufacture of very fine fiber fleece which, depending on the composition of the starting materials and their subsequent processing, exhibits different material properties.
Centrifugal spinning methods have been known for many years. They have their origin in glass fiber production and have also been used for some time to process polymer materials. Methods for manufacturing fiber fleece are explained in the following patents: U.S. Pat. No. 4,666,782; U.S. Pat. No. 4,790,736; U.S. Pat. No. 4,898,634; U.S. Pat. No. 4,440,700; U.S. Pat. No. 4,937,020; U.S. Pat. No. 4,277,436; and Canadian Patent 1,155,619. The contents of each of these patents is incorporated herein by reference in their entirety.
In the methods for manufacturing fiber fleece from synthetic material set forth in these patents, a polymer granulate is usually melted in an extruder and delivered at a pressure of up to 200 bars to a spinning rotor rotating at 3,000 to 11,000 rpm. The rotor typically is heated by means of electrical heating elements. The fibers emerging radially from the spinning rotor are then deflected and solidified and laid down on a conveyor belt to form a flat structure.
The methods used to lay down fine fiber-fleece fibers as a fleece are often very complicated and cumbersome, as described, for example, in DE PS 3 215 810 C2. If the fibers are fed through a liquid cooling medium, additional drying of the webs is also necessary.
In the known methods for statically electrically charging fiber fleece for filtration purposes, discharge often occurs after relatively short usage of the filter element, resulting in a significantly reduced filter effect.
There remains a need for an improved technique for manufacturing a flat textile such that filter elements made of fiber fleece remain capable of carrying filtration-effective charges even after prolonged use.